Bale stacker

ABSTRACT

A bale stacker for stacking papermaking pulp bales, comprising two sets of lifting forks ( 17 - 19; 20 - 22 ), which are directed to each other for together lifting bales, and a conveying means ( 12, 13 ) for inserting a new bale ( 14 ) beneath the lifted bales. The lifting forks are horizontally movable between advanced active lifting position and inactive retracted position and have forward portions ( 23 ) with continuously decreasing thickness. The drive means for the lifting forks comprise a motor ( 37 ) and a freewheel clutch for lifting and lowering the lifting forks, so that the lowering movement for both sets of lifting forks automatically and individually are adapted to their pulling-out movement when they rest on the underlying bale, although the speed of the drive motors ( 37 ) of the drive means which operate synchronized need not be controlled.

TECHNICAL FIELD OF THE INVENTION

[0001] This invention relates to a bale stacker for stacking pulp bales,comprising lifting forks driven by a drive means for lifting balesalready stacked, and a conveying means for inserting a new bale beneaththe lifted bales, which lifting forks are movable horizontally betweenadvanced active lifting position and inactive retracted position andhave points (23) with continuously decreasing thickness.

BACKGROUND OF THE INVENTION AND STATE OF ART

[0002] Papermaking pulp bales usually are held together by being tiedaround with steel wire. A number of such bales are then stacked in ausual manner and tied around with steel wire to form an assembled balestack. Previously stackers were used which placed a new bale above analready stacked bale. At present stackers are used which lift thealready stacked bales and insert a new bale beneath the already liftedbales. The lifted bale stack is then lowered onto the lowermost bale,and the lifting forks are pulled out so that the stack thuds down ontothe lowermost bale with a loud sound. Papermaking pulp bales often arenot entirely rectangular, and the sound is especially loud when a balethuds down onto a bale with an inclined upper surface. It can evenhappen that one or several bales fall off the stack. WO-00/09430 showsexamples of known bale stackers.

THE OBJECT OF THE INVENTION AND A SHORT DESCRIPTION THEREOF

[0003] An object of the invention is to offer in a simple andcost-effective way a rapid and efficient bale stacker, which isrelatively quiet and operates with greater safety than previously knownbale stackers. This object is achieved in principle in that the drivemeans for the lifting forks comprises a motor and a freewheel clutch forlifting and lowering the lifting forks. The invention is defined in theattached claims.

SHORT DESCRIPTION OF THE DRAWINGS

[0004]FIG. 1 is a lateral view of a bale stacker as an embodiment of theinvention. The view is taken as indicated by the arrows 1-1 in FIG. 2.

[0005]FIG. 2 is a top view of the bale stacker shown in FIG. 1.

[0006]FIG. 3 is a lateral section of the bale stacker taken as indicatedby the arrows 3-3 in FIG. 1.

DESCRIPTION IN DETAIL OF THE EMBODIMENT SHOWN AND PREFERRED

[0007] The bale stacker shown in the Figures has a rigid steel frame 11fastened with bolts on the floor. In the frame a conveyor 12,13 islocated which from an external conveyor (not shown) feeds bales 14 oneby one (only one bale is shown and only in FIG. 1) to stacking positionin the bale stacker and then feeds a bale stack out to a second conveyor(not shown). It is important to position a bale accurately, and the balestacker has several positioning means, which are not shown anddescribed, because they belong to known and conventional art.

[0008] On each side of the conveyor 12,13 a lifting means 15,16 islocated, both of which have a number (at the embodiment shown three) oflifting forks 17,18,19 and 20,21,22, respectively, which at the lowerend positions are slightly lower than the conveyors. The outer portions23 of the lifting forks have continuously decreasing thickness, as shownin FIG. 1. The lifting forks, for example, can have a thickness of 30mm, and the chamfered front portion can be chamfered to a thickness of5-10 mm at the point. The entire portion of the lifting forks which isinserted beneath a bale suitably can be chamfered.

[0009] The lifting means 15,16, thus, are the drive means for liftingand lowering the lifting forks. They are identical, and only the liftingmeans 15 shall be described in detail with reference to FIG. 3. It has atravelling crab 30 (the lifting means 16 has a corresponding travellingcrab 29), which runs in two vertical guides 31,32. It is driven alongthe guides by two endless chains 33,34, which run over two driven uppersprockets 35,36 and two lower free-rolling sprockets 47,48. A motor 37drives synchronously the two sprockets 35,36 over a gear box 38. Thesprockets 35,36 have built-in freewheel clutches of conventional kind,and the freewheel clutches, therefore, are not shown. A power means inthe form of a cylinder 42 is coupled to the three lifting forks 17,18,19coupled together, so that they are movable horizontally in theirlongitudinal direction between an advanced active lifting position and aretracted inactive position. The lifting forks are guided in guides43,44,45 on the travelling crab 30 and are arranged so that they followalong in the vertical movements of the travelling crab 30. The crab hasan outward movable positioning means 46, which is controlled by a powermeans (not shown), for example a cylinder.

[0010] A bale stacking cycle will now be described.

[0011] An external conveyor (not shown) moves a bale in to the conveyor12,13, which moves the bale to a hinged stop means (not shown), whichplaces the bale in correct position in the longitudinal direction of theconveyor. Thereafter the bale is positioned in correct position in thedirection transverse to the conveyor by guide pads 46 of the travellingcrabs. The lifting forks 17-19 and 20-22 of the two travelling crabs29,30 are in advanced position, but are in their lower end positions, inwhich they are on a lower level than the conveyor and, therefore, do notdisturb the bale 14. At the positioning of the bale the travelling crabs29,30 are moved synchronously upward so that their opposite directedlifting forks will lift the bale. The bale having been lifted, a newbale is moved in beneath the lifted bale and is positioned inlongitudinal and transverse direction by positioning means (not shown).The travelling crabs are now moved synchronously downward, and when theyarrive at the lower bale, their lifting forks are pulled outward bytheir respective cylinders so that they release the bale, and thetravelling crabs can continue to be moved downward to their lower endpositions. There the lifting forks are moved in to each other again, andthen the travelling crabs are again moved up, and the lifting forks thistime lift the two bales so that a third bale can be inserted beneaththem, and they can be lowered down upon this bale, so that the balestack now comprises three bales. In this way the desired number of balescan be stacked, and the conveyor 12,13 can then move the bale stack toan external conveyor, which moves the bale stack to a station to be tiedaround.

[0012] Due to the chamfering of the forks, a lifted bale can land softlyon the lower bale, provided that the vertical movement of the fork issynchronous with its pulling-out movement. Owing to the fact that thetravelling crabs, and thereby the lifting forks, are driven viafreewheel clutches, it is ensured that this movement will besynchronous, without requiring a complicated control system, because thesynchronized motors can operate at constant speed, and the verticalspeed of the lifting forks still is automatically adapted when thelifting forks rest on the lower bale. The two pairs of lifting forks arein this way adapted individually to the upper surface of the bale, andboth pairs are pulled out resting on the upper surface of the lower baleeven when said upper surface is inclined. As soon as the lifting forksdo not rest any longer on the bale, the travelling crabs, and therebythe lifting forks, resume their speed downward determined by the motors.The lifting motors are permanently synchronized, and the verticalmovement of the lifting forks is synchronized until a freewheel isactivated at the lowering movement. When both pairs of lifting forks arelowered to their lower end positions, they are again synchronized beforethe next lifting movement.

[0013] The invention is described with reference to the stacking ofbales with papermaking pulp, but can, of course, be used also for thestacking of other types of bales.

[0014] The invention, of course, is not restricted to the embodimentshown, but can be varied within the scope of the claims with referenceto the description.

1. A bale stacker for stacking pulp bales, comprising lifting forks(17-19; 20-22) driven by a drive means (15,16) for lifting bales alreadystacked, and a conveying means (12,13) for inserting a new bale (14)beneath the lifted bales, which lifting forks are horizontally movablebetween advanced active lifting position and inactive retractedposition, and have forward portions (23) with continuously decreasingthickness, characterized in that the drive means (15,16) for the liftingforks (17-19; 20-22) comprise a motor (37) and a freewheel clutch forlifting and lowering the lifting forks.
 2. A bale stacker as defined inclaim 1, characterized in that the lifting forks (17-19; 20-22) arecarried by a travelling crab (29,30), which is guided in vertical guides(31,32) and is driven by a chain (33,34), which runs over a drivingsprocket (35,36), and the freewheel clutch is assembled with the drivingsprocket.
 3. A bale stacker as defined in claim 1, characterized in thatit comprises two sets of lifting forks (17-19; 20-22), which aredirected to the conveyor means (12,13) in order to commonly be able tolift a bale (14) from the conveying means, and the conveying means isarranged to convey a bale in the direction transverse the lifting forks.4. A bale stacker as defined in claim 3, characterized in that each setof lifting forks (17-19; 20-22) is carried by a travelling crab (30),which is guided in vertical guides (31,32) and is driven by a chain(33,34), which runs over a driving sprocket (35,36), and the freewheelclutch is assembled with the driving sprocket.
 5. A bale stacker asdefined in claim 4, characterized in that the chains (33,34) for the twosets of lifting forks (17-19; 20-22) are driven by motors operatingsynchronously.